49.1 Easy Customization Interface

Emacs has many settings which you can change. Most settings
are customizable variables (see Variables), which are also
called user options. There is a huge number of customizable
variables, controlling numerous aspects of Emacs behavior; the
variables documented in this manual are listed in Variable Index. A separate class of settings are the faces, which
determine the fonts, colors, and other attributes of text
(see Faces).

To browse and alter settings (both variables and faces), type
M-x customize. This creates a customization buffer, which
lets you navigate through a logically organized list of settings, edit
and set their values, and save them permanently.